A method of measuring flow through an orifice includes flowing a fluidthrough the orifice, measuring a pressure drop across the orifice and atemperature ofthe fluid at one or more predetermined intervals, calculating an intervalamount offlow of fluid through the orifice for each interval based on the measuredpressure dropand temperature of the fluid, and summing the calculated interval amounts offlow offluid to determine an accumulated amount of fluid flow through the orifice